A fixing/releasing mechanism is used to mechanically connect an element to another element. The current apparatuses such as medical apparatuses increasingly tend to be portable and detachable to meet the portablility and use requirement in various environments. For example, the U.S. patent application US2003/0167074A1 published on Sep. 4, 2003, as shown in FIG. 1, reveals that an extended base of a cart has a fixing/releasing mechanism to couple and snap fit a portable medical apparatus placed on the extended base. However, the fixing/releasing mechanism fixes the medical apparatus to the base only by means of front and rear clamps 40, 78, 80 etc. and requires manual operation for fixing and positioning so that the fixing and mounting process is inconvenient and when the portable medical apparatus is removed, it is likely to be damaged by impingement of impact force in opposite direction generated by the clamps 40, 78, 80 when breaking away from the medical apparatus.